Matarka        33°15’N, 02°45’W

Eastern, Morocco

Confirmed fall: 2018 Jan 5

Classification: Ordinary chondrite (L6)

History: In the evening of January 5, 2018, between 21:00 and 22:00 local time, a bright fireball was witnessed by people in the communities Tendrara, Anoual and Bouarfa in northeastern Morocco. The event was described as of several seconds duration, and with a green color. At least one fragmentation was described by one observer. No sound phenomena were reported. Eyewitness accounts were collected in May and June 2018 by Abdelaziz Mouadine from two eyewitnesses, Ali Atewi (Matarka) and Keser Haron (Talsint). On February 5, one month after the event, a single meteorite was found near Matarka, and subsequently offered to Moroccan meteorite dealers. Eventually it was purchased by Aid Mohamed, and on April 27, 2018, it was sold to M. Jost in Foum Zgouid, near Zagora, Morocco.

Physical characteristics: Single stone with dimensions 7.5 × 6.5 × 6.5 cm and a mass of 538 g. Angular shape with smoothly rounded edges, indicating significant ablation and extended atmospheric flight as individual. The mass displays a fresh appearance and, apart from a small (1 × 3 cm) area, is completely covered in fresh fusion crust. One area is rough and shows melting lips along the edge, probably the result of a fragmentation at high altitude. The matrix shows a bright ash-colored appearance. Neither the exterior nor the interior shows oxidation of metal.

Petrography: (B. Hofmann, NMBE, J. Pape, UBE/NMBE): Strongly recrystallized, chondrules only present as relicts. Mineral grains (except Fe metal) show strong irregular fracturing. Mean size of plagioclase grains is 80-150 μm. Very minor rust staining around metal grains. Rare small (to 10 μm) native Cu at troilite-iron boundaries. Troilite shows lamellar twinning and contains inclusions of pentlandite to 20 μm. Below fusion crust cracks filled with remobilized troilite.

Geochemistry: Electron microprobe analysis (J. Pape, UBE/NMBE): olivine Fa_24.3±0.3 (range Fa_23.8-24.7; n=17), pyroxene Fs_20.5±0.2Wo_1.5±0.2 (range Fs_20.1-20.5Wo_1.1-1.7; n=17), plagioclase An_10.4±0.3Or_5.9±1.1 (range An_9.9-10.9Or_3.9-7.9; n=13). Cosmogenic radionuclides: (Å. Rosén, Germanium Material and Meteorite Screening Experiment): Gamma-spectroscopy performed in November 2018 showed the presence of the following short-lived radionuclides (dpm/kg as of 5 January 2018): ⁴⁶Sc 5.0±1.5/-1.3, ⁵⁴Mn 44.5±4.7/-3.3, ⁵⁷Co 4.7±0.8/-0.3, ²²Na 71.8±6.0/-5.2, ²⁶Al 34.4±1.7/-3.9 and ⁶⁰Co 0.36±0.07/-0.09. The ²²Na/²⁶Al activity ratio of 2.16(+0.09,-0.08) and activities of ⁵⁴Mn and ⁴⁶Sc are in the range of recent falls. The activity ratio of ⁵⁴Mn/⁴⁶Sc is 8.9. Activity ratios of fresh OC falls are 8.1-17.2 (mean 11.1±2.8, median 10.0, based on 27 analyses in Evans et al. (1982). Assuming the lowest reported initial ratio of 8.1 at the time of fall, the actual fall date would have been just ~16 days before January 5, 2018. The fall must thus very likely have occurred after December 20, 2017, even with this unlikely assumption. Low ²⁶Al and ⁶⁰Co indicate a small pre-atmospheric size.

Classification: Ordinary chondrite (L6), shock stage S3, no weathering (W0).

Specimens: 22.2 g and one polished thin sections at NMBE. Main mass with Beat Booz.